Isozyme-Specific Ligands for O-acetylserine sulfhydrylase, a Novel Antibiotic Target

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dc.contributor.authorFrancesca Spyrakisen_US
dc.contributor.authorRatna Singhen_US
dc.contributor.authorPietro Cozzinien_US
dc.contributor.authorBarbara Campaninien_US
dc.contributor.authorEnea Salsien_US
dc.contributor.authorPaolo Felicien_US
dc.contributor.authorSamanta Rabonien_US
dc.contributor.authorPaolo Benedettien_US
dc.contributor.authorGabriele Crucianien_US
dc.contributor.authorGlen E. Kelloggen_US
dc.contributor.authorPaul F. Cooken_US
dc.contributor.authorAndrea Mozzarellien_US
dc.date.accessioned2015-01-23T17:17:48Z
dc.date.accessioned2016-03-30T15:36:15Z
dc.date.available2015-01-23T17:17:48Z
dc.date.available2016-03-30T15:36:15Z
dc.date.issued2013-10-22en_US
dc.descriptionen_US
dc.descriptionConceived and designed the experiments: FS PC BC ES AM. Performed the experiments: FS RS ES PF SR. Analyzed the data: FS BC ES PF GEK PFC AM. Contributed reagents/materials/analysis tools: PC PB GC. Wrote the paper: FS GEK BC AM.en_US
dc.description.abstractThe last step of cysteine biosynthesis in bacteria and plants is catalyzed by O-acetylserine sulfhydrylase. In bacteria, two isozymes, O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B, have been identified that share similar binding sites, although the respective specific functions are still debated. O-acetylserine sulfhydrylase plays a key role in the adaptation of bacteria to the host environment, in the defense mechanisms to oxidative stress and in antibiotic resistance. Because mammals synthesize cysteine from methionine and lack O-acetylserine sulfhydrylase, the enzyme is a potential target for antimicrobials. With this aim, we first identified potential inhibitors of the two isozymes via a ligand- and structure-based in silico screening of a subset of the ZINC library using FLAP. The binding affinities of the most promising candidates were measured in vitro on purified O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B from Salmonella typhimurium by a direct method that exploits the change in the cofactor fluorescence. Two molecules were identified with dissociation constants of 3.7 and 33 µM for O-acetylserine sulfhydrylase-A and O-acetylserine sulfhydrylase-B, respectively. Because GRID analysis of the two isoenzymes indicates the presence of a few common pharmacophoric features, cross binding titrations were carried out. It was found that the best binder for O-acetylserine sulfhydrylase-B exhibits a dissociation constant of 29 µM for O-acetylserine sulfhydrylase-A, thus displaying a limited selectivity, whereas the best binder for O-acetylserine sulfhydrylase-A exhibits a dissociation constant of 50 µM for O-acetylserine sulfhydrylase-B and is thus 8-fold selective towards the former isozyme. Therefore, isoform-specific and isoform-independent ligands allow to either selectively target the isozyme that predominantly supports bacteria during infection and long-term survival or to completely block bacterial cysteine biosynthesis.en_US
dc.description.peerreviewYesen_US
dc.description.peerreviewnoteshttp://www.plosone.org/static/editorial#peeren_US
dc.identifier.citationSpyrakis F, Singh R, Cozzini P, Campanini B, Salsi E, et al. (2013) Isozyme-Specific Ligands for O-acetylserine sulfhydrylase, a Novel Antibiotic Target. PLoS ONE 8(10): e77558. doi:10.1371/journal.pone.0077558en_US
dc.identifier.doi10.1371/journal.pone.0077558en_US
dc.identifier.urihttp://hdl.handle.net/11244/14099
dc.language.isoen_USen_US
dc.publisherPLos Oneen_US
dc.relation.ispartofseriesPLoS ONE 8(10):e77558en_US
dc.relation.urihttp://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0077558en_US
dc.rightsAttribution 3.0 United Statesen_US
dc.rights.requestablefalseen_US
dc.rights.urihttp://creativecommons.org/licenses/by/3.0/us/en_US
dc.subjectPLOSen_US
dc.subjectPublic Library of Scienceen_US
dc.subjectOpen Accessen_US
dc.subjectOpen-Accessen_US
dc.subjectScienceen_US
dc.subjectMedicineen_US
dc.subjectBiologyen_US
dc.subjectResearchen_US
dc.subjectPeer-reviewen_US
dc.subjectInclusiveen_US
dc.subjectInterdisciplinaryen_US
dc.subjectAnte-disciplinaryen_US
dc.subjectPhysicsen_US
dc.subjectChemistryen_US
dc.subjectEngineeringen_US
dc.titleIsozyme-Specific Ligands for O-acetylserine sulfhydrylase, a Novel Antibiotic Targeten_US
dc.typeResearch Articleen_US

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